Torque fluctuation absorbing apparatus

ABSTRACT

A torque fluctuation absorbing apparatus includes drive plates coupled to an input shaft from an engine, a flywheel supported rotatably on the input shaft, a driven disc radially outwardly extending between the opposed drive plates and fixed on the flywheel, and a pair of L-shape thrust members located in a space between the opposed drive plates and forming a liquid chamber. The lining secured to outer side surfaces of the thrust members are brought into frictional engagement with inner side surfaces of the drive plates when a liquid pressure in the chamber is increased and the thrust members are axially moved.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a torque fluctuation absorbingapparatus which is used for absorbing the torque vibration from an inputshaft coupled to an engine.

2. Description of the Related Art

It is known that a rotational torque from a vehicle's engine has anundesired range of torque fluctuation due to the cycle-by-cyclevibration associated with combustion of the engine and such torquefluctuation or vibration should be absorbed in a power train of thevehicle. In the event rotational torque having a large torsionalfluctuation is directly supplied to a power transmission or gear box, itwould be damaged, consequently, the input shaft, such as a crank shaftof the engine, provided with a flywheel which is cooperated with aclutch mechanism having a damper.

For purpose of decreasing the range of the torque fluctuation at lowengine speed, the inertia member such as the flywheel is divided into anannular driving plate member and a flywheel member, and the damper isinterposed between the driving plate and the flywheel member.

The conventional structures having the divided inertia members and theinterposed damper are described in the specifications of U.S. Pat. No.4,274,524, U.S. Pat. No. 4,739,866 and U.S. Pat No. 5,180,044.

As is apparent from the disclosures of these prior specifications, theconventional damper is composed of coil springs which are deformed bythe twist or rotation of the driving plate member relative to theflywheel member, or a combination of coil springs and viscous liquid.

It is desired that the damping action be low when a small range oftorque fluctuation is produced at a high engine speed, and that thedamping action be high when a large range of torque fluctuation isproduced at a low engine speed such as below the engine idling speed.However, the conventional damping mechanisms are insufficient to realizethe damping actions as described above.

SUMMARY OF THE INVENTION

It is therefore one object of the present invention to provide a torquefluctuation absorbing apparatus which will obviate the conventionaldrawbacks as mentioned above.

It is another object of the present invention to provide a torquefluctuation absorbing apparatus which will absorb the undesired torquevibration at low engine speed and also at high speed.

In order to accomplish the above object, this invention provides atorque fluctuation absorbing apparatus comprising drive plate meanscoupled to a driving shaft of a power source means, flywheel meansarranged in co-axial relation with the drive plate means and rotatedrelative to the drive plate means, and damper means providing a torquetransmission path between the drive plate means and the flywheel means,the damper means producing damping actions due to the pressuredifference of a viscous liquid and frictional resistance generated whena liquid pressure is applied to the drive plate means.

There is further provided a torque fluctuation absorbing apparatuscomprising a first drive plate coupled to an input shaft, an annularouter ring fixed on an outer peripheral end portion of the first driveplate, a second drive plate opposed to the first drive plate and fixedto the outer ring, a flywheel member supported rotatably on the inputshaft, a driven disc secured to the flywheel and extending radiallyoutwardly between both the drive plates, resilient means carried on thedriven disc for transmitting a rotational torque from the drive platesto the driven disc, a pair of L-shape thrust members arranged betweenthe opposed drive plates to define a liquid chamber, piston meanslocated in the liquid chamber and slidable together with the thrustmembers in a circumferential direction when the driven disc is twistedrelatively to the drive plates, choke means formed in the liquidchamber, lining means interposed between inner side surfaces of thedrive plates and outer side surfaces of the thrust members for producinga frictional resistance when a liquid pressure in the chamber isincreased due to the circumferential movement of the piston means towardthe choke means, and clutch means cooperating with the flywheel andcoupled to an output shaft.

Under a state where a sudden torque fluctuation is produced, the driveplates are considerably twisted relative to the driven disc so that thepistons are moved in the circumferential direction together with thedriven disc and a pressure difference across each choke in the viscousliquid chamber is generated. The pressure difference forces the thrustmembers to be axially moved and the linings are brought into frictionalengagement with the drive plates. This will absorb the sudden torquefluctuation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional view of an apparatus which embodies oneembodiment of the present invention; and

FIG. 2 is a fragmentary sectional plane view of the apparatusillustrated in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to drawings, there is shown one embodiment of the presentinvention adapted in a torque fluctuation absorbing apparatus forautomotive vehicles which is indicated by reference numeral 1 andcoupled to an engine crank shaft, that is a driving or input shaft 2.

The apparatus 1 includes a flywheel 12 and a cover 4 secured to one sideof the flywheel 12. A driven or output shaft 5 is provided at its oneend with a clutch disc 6 having a lining 7 slidable in relation to oneside surface of the flywheel 12. The lining 7 is urged to one sidesurface of the flywheel 12 through a pressure plate 9 which iscooperates with a diaphragm spring 8 so as to make a frictional abutmentcondition between them. The advance movement of a collar 10 along theoutput shaft 5 forces the lining 7 to be disengaged from one sidesurface of the flywheel 12.

An inertia member is divided into the flywheel 12 and a drive platemember which is composed of a first drive plate 11 and a second driveplate 15. These drive plates 11, 15 are disposed in the mannerillustrated in FIG. 1. An outer ring 13 having a ring gear 14 is securedto outer peripheral end portions of these drive plates 11, 15. Theflywheel 12 is supported on the input shaft 2 through a bearing 16 and aring 17.

A driven disc 18 extends outwardly between the opposed drive plates 11,15 and an inner peripheral end portion thereof is secured to thecorresponding portion of the flywheel 12 by means of the ring 17 andrivets 33. A seal member 19 is interposed between the ring 17 and thesecond drive plate 15. Three holes or cut-out portions 20 are made onthe driven disc 18 with even spaces between these cut-out portions 20 ina rotational direction. Three sets of springs each comprising a coupleof springs 21a, 21b are disposed within each cut-out portion 20. Theout-side spring 21a is parallel to the in-side spring 21b in a radialdirection and these springs 21a, 21b are seated at both ends on springseat members 22 which each have projections 32 to be inserted intocentral hollow portions of the springs 21a, 21b. Separators 23 aredisposed between each outside and in-side spring 21a, 21b which form aset to restrict unexpected movement of the spring seat members 22 andprevent interference of the out-side and in-side springs 21a, 21b.

The drive plates 11, 15 have concave portions 35, 36 which approach toeach other and extend radially and circumferentially to abut on thespring seat members 22 disposed at end places of each cut-out portion 20and a rotational torque is transmitted from the drive plates 11, 15 tothe driven disc 18. When the drive plates 11, 15 are twisted to thecircumferential front side or rear side relative to the driven disc 18,the concave portions 35, 36 for engagement with the spring seat members22 deform the springs 21a, 21b. The deformation of the springs 21a, 21bassists in transmitting the rotational torque from the drive plates 11,15 to the driven disc 18 and in absorbing torsional vibration.

Both the side surfaces of each spring seat member 22 are in slidablecontact with opposed side surfaces of the drive plates 11, 15 and eachspring seat member 22 is moved along the opposed drive plates 11, 15without undesirable inclination of the springs 21a, 21b. It is desiredto form holes or grooves on the spring seat members 22 to reducefrictional resistance. The spring arrangement described above enables anaxial length of the springs 21a, 21b to be shortened and a largetorsional vibration to be absorbed.

L-shape thrust members 25a, 25b are disposed in a space defined by theopposed drive plates 11, 15 and the annular outer ring 13, but outwardthe outer peripheral end portion of the driven disc 18. The axiallyextending portions of the thrust members 25a, 25b are placed over oneanother to define an annular liquid chamber 26 for viscous liquid. Thechamber 26 is divided into four chambers by four slidable pistons 27inwardly protruding from the inner peripheral surface of the outer ring13 and opening to an inside. Opposed legs of each piston 27 are held atcut-out places formed on the axially extending portions of the thrustmembers 25a, 25b. Radial projections 28 of the driven disc 18 areinserted into the opening of each piston 27 so that the rotational twistof the driven disc 18 relative to the drive plates 11, 15 causes thethrust members 25a, 25b and the pistons 27 to be rotated in thecircumferential direction.

Side surfaces of the thrust members 25a, 25b which oppose the inner sidesurfaces of the drive plates 11, 15 are provided with linings 24a, 24bfor clutch engagement therewith.

Stoppers 29 are provided between two pistons 27 and secured to the innerperipheral surface of the outer ring 13 to form a choke 30 between theaxially extending portion of the thrust member 25b and an inner surfaceof each stopper 29, respectively. Viscous liquid such as grease isfilled in the chamber 26. The left side and right side spaces or volumes26a, 26b of each stopper 29 are varied depending upon thecircumferential movement of the pistons 27.

A rapid torque fluctuation applied to the drive plate 11 is transmittedto the driven disc 18 through the springs 21a, 21b so that theprojections 28 of the driven disc 18 press the pistons 27 in onedirection. At this stage, the circumferential movement of each piston 27as indicated by an arrow in FIG. 2 will compress the liquid in the firstspace 26a divided by the stopper 29 and the compressed liquid in thefirst space 26a will flow therefrom to the second space 26b through eachchoke 30. The flow resistance produced when the viscous liquid flowsthrough each choke 30 converts the sudden torque fluctuation into athermal energy. As a consequence, the range of the large torquefluctuation becomes small and a constant speed rotation of the drivendisc 18 is developed. In this case, the pressure difference across eachstopper 29 is diminished and the flow resistance by each choke 30becomes small so that a torque transmission through the coil spring 21a,21b is performed.

The axially extending annular portions 25c, 25d of the L-shape thrustmembers 25a, 25b are placed over one another to be axially slidable withrespect to each other and press the linings 24a, 24b on the inner sidesurfaces of the first and second drive plates 11, 15 when high pressureis produced in each space 26a or each space 26b. The linings 24a, 24bsecured to the outer side surfaces of the members 25a, 25b are broughtinto frictional engagement on the inner side surfaces of the driveplates 11, 15 due to the pressure in the space 26a or 26b, so that thefrictional resistance due to the linings 24a, 24b and the flowresistance due to the chokes 30 are generated and a rotational torquehaving a small range of torsional fluctuation is transmitted to thedriven disc 18. This is effective in the low speed range of the engineand the objectionable torque transmission to the output shaft 5 at lowengine speed is avoided.

Plural cut-outportions 34 are formed on the inner peripheral end portion12 with even space in a circumferential direction, and the bearing 16and the oil seal member 19 are partially opened toward the atmospherethrough the cut-out portions 34 to supply fresh air to the bearing 16and the oil seal member 19. This makes it possible to efficiently coolthe bearing 16 and the oil seal member 19.

Obviously, many modifications and variations may be made in light of theabove teaching and the invention should be defined only by the appendedclaims as follows.

What is claimed is:
 1. A torque fluctuation absorbing apparatuscomprising a first drive plate coupled to an input shaft, an annularouter ring fixed on an outer peripheral end portion of said first driveplate, a second drive plate opposed to said first drive plate and fixedto said outer ring, a flywheel member supported rotatably on said inputshaft, a driven disc secured to said flywheel and extending radiallyoutwardly between said first and second drive plates, resilient meanscarded on said driven disc for transmitting a rotational torque fromsaid first and second drive plates to said driven disc, a pair ofL-shaped thrust members arranged between the opposed first and seconddrive plates to define a liquid chamber, piston means located in saidliquid chamber and slidable together with said pair of thrust members ina circumferential direction when said driven disc is twisted relativelyto said first and second drive plates, choke means formed in said liquidchamber, lining means interposed between inner side surfaces of saidfirst and second drive plates and outer side surfaces of said thrustmembers for producing a frictional resistance when liquid pressure insaid liquid chamber is increased due to circumferential movement of saidpiston means toward said choke means, and a clutch device cooperatingwith said flywheel and coupled to an output shaft.
 2. A torquefluctuation absorbing apparatus as set forth in claim 1, wherein saidlining means includes linings fixed on the outer side surfaces of saidthrust members and brought into frictional contact with the inner sidesurfaces of said drive plates when the opposed thrust members are movedin an axial direction due to the increase in liquid pressure in saidchamber.
 3. A torque fluctuation absorbing apparatus as set forth inclaim 2, wherein said driven disc is provided with a plurality ofwindows, said resilient means including three sets of springs eachhaving at least two coil springs which are disposed in the windowsformed on said driven disc, and spring seat members receiving ends ofsaid coil springs.
 4. A torque fluctuation absorbing apparatus as setforth in claim 3, wherein each L-shaped thrust member includes anaxially extending portion, said choke means including stoppers extendingradially inwardly from said outer ring to define chokes between innerfaces of said stoppers and the axially extending portion of one of saidthrust members.
 5. A toque fluctuation absorbing apparatus as set forthin claim 1, wherein said pair of L-shaped thrust members each have aradially extending portion and an axially extending portion locatedradially inwardly of the radially extending portion, said lining meansincluding a lining provided on an outer surface of the radiallyextending portion of each thrust member, the axially extending portionof one thrust member overlapping the axially extending portion of theother thrust member.
 6. A torque fluctuation absorbing apparatus as setforth in claim 1, wherein said piston means includes four pistonsextending inwardly from an inner peripheral surface of said outer ringto divide said liquid chamber into four chambers.
 7. A torquefluctuation absorbing apparatus as set forth in claim 6, wherein eachpiston includes a pair of opposed legs between which is defined anopening, said driven disc including a plurality of projections which areeach disposed in one of the openings defined by the opposed legs of oneof the pistons.